Refrigeration equipment



Feb. 14, 1961 E. F. GYGAX 2,971,347

REFRIGERATION EQUIPMENT Filed Aug. 2, 1956 2 Sheets-Sheet 1 IN V EN TOR.

. ATTORAEY Feb. 14, 1961 Filed Aug. 2, 1956 E. F. GYGAX 2,971,347

REFRIGERATION EQUIPMENT 2 Sheets-Sheet 2 v INVENTORm ATTORNEY United States Patent 2,971,347 REFRIGERATION EQUIPMENT Ernest F. Gygax, Glendale, Mo., assignor, by mesne asslgnments, of one-half to Edward T. Wright, Brentwood, Mo., and one-half to Rey Eilers, Clayton, Mo.

Filed Aug. 2, 1956, Ser. No. 601,824 12 Claims. (Cl. 62-183) This invention relates to improvements in refrigeration equipment. More particularly, this invention relates to improvements in cooling apparatus for the condensing coil of a refrigeration system.

It is therefore an object of the present invention to provide an improved cooling apparatus for the condensing coil of a refrigeration system. r

In the operation of a compression-expansion refrigeration system, a gas is compressed to increase its. sensible heat; and thereafter that increased heat is removed and the gas permitted to expand. The removal of that increased heat enables the gas in the expansion coil to absorb heat and thereby provide a cooling efiect. Customarily, the increased sensible heat of the gas in a cornpression-expansion refrigeration system is removed in a condenser; and that condenser is usually cooled by water or air. Water is a good coolant for. condensers because its temperature .can easily be :kept within narrow, and

appropriately low, limits. However, the use of water as a coolant introduces the critical problems of rust, corrosion and scale. Furthermore the use of water as a coolant involves the cost of wasting large quantities of water or of installing water-cooling equipment. For these various reasons, theuse of water as the coolant of a conden ser for a compression-expansion refrigeration system can be objectionable. The present invention obviates this objection by providing air cooling of the condenser of a compression-expansion refrigeration system.

'Actually, of course, the concept of using air to cool the.

pressure diiterentials ,in that system. This is due to the fact that airternperatures can vary Widely during a twenty four hour period, and can vary even more widely from day to day or from week to week. In particular, am-

bientjair temperatures can, in many places, rise to levels as high as one hundred degrees Fahrenheit during the heat of the day and fall to levels as lowas seventy degrees Fahrenheit during the cool of the following night. This means that the head pressure of the compressor in an aircooled compression-expansion refrigeration system can rise tolevels as high as onenhundred and fifty pounds 2,971,347 Patented Feb. 14, 1961 "Ice,

with an orifice that would satisfy the expansion coil when the pressure difierential was low, that valve would overfeed that coil when the pressure differential was high. On the other hand, if an expansion valve was provided with an orifice that would satisfy the expansion valve when the pressure differential was high, that valve would starve the system when the pressure differential was low. For these reasons, the use of air as the coolant for the condensing coil of compression-expansion refrigeration systems has been subject to objection. The present invention minimizes that objection by providing a cooling apparatus, for the condensing coil of a compression-expansion refrigeration system, that cools that coil with air but that also reduces the variations in pressure differential in that system. That cooling apparatus makes it possible to provide an expansion valve that can satisfy the expansion coil without overfeeding that coil. It is therefore an object of the present invention to provide a cooling apparatus that air-cools the condensing coil of a compression-expansion refrigeration system while minimizing variations in the pressure differentials in that system.

The present invention minimizes variations in the pres-, sure differentials in an air-cooled compression-expansion refrigeration system by varying the volume of air passing over the condensing coil to keep the compressor head pressure relatively constant. When the temperature of the ambient air is high, the cooling apparatus provided by the present invention will pass a large volume of air over the air-cooled condenser and thereby keep the head pressure of the compressor from rising unduly. When the temperature of. the ambient air is low,,tl1at cooling apparatus will pass a'smaller volume of air over that condenser, thereby keeping the head pressure of the compressor from falling unduly. Moreover, when the temperature of the ambient air changes, that apparatus will automatically change the volume of air moved over that condenser. In this way, the head pressure of the compressor is maintained within close limits and such a pressure can coact with the suction pressure of the compressor to keep the pressure differentialsin the expansion-com:-

pression system within reasonable limits. It is therefore,

an object of the present invention to provide a cooling apparatus that varies the volume of air passed over the air-cooled condenser of a compression-expansion refrigeration system to keep the head pressure of the comper square inch and can fall to levels as low as eighty pound per square inch in less than twenty four hours;

Because the steady-state suction pressures of a compressor for a compression-expansion refrigeration systempossible to operate thesystem efiiciently; Inparticular, it is impossible to select. an expansion valve with an ori-i fice that can operate ,efiiciently. over a wide, range of pres sure differentials. If an expansion valve was provided an infinite number of speeds for that motor and blower."

The use of a hydraulic motor to drive the blower for frigeration system by mounting a hydraulic motor adja-- cent that coil, by mounting a blower on theshaft of that hydraulic motor, and by varying the speed ofthat hydraulic motor. hydraulic fluid issuing from a hydraulic pump; and that pump can be driven by the power source for the compressor of the compression-expansion refrigeration systern or it can be driven by a separate power source. The hydraulic fluid that is supplied to the hydraulic motor by the hydraulic pump can be valved to provide the required variations in the speed of that hydraulic motor and therefore in the speed of, the blower mounted on the shaft of that motor. That valving can provide an infinite number of speeds for the hydraulic motor and the blower, and such a range of speeds makes it possible to hold the head pressure of the compressor within the desired limits. It

is therefore an object of the present invention to mount a hydraulic motor adjacent the condensing coil of a com;

pression-expansion refrigeration system, to mount a blower on the shaftof that motor, and to valve thehy draulic fluid moving tofthathydraulic motor to provide The hydraulic motor will be driven by.

the condensing coil of the compression-expansion refrigeration system is very desirable because such a motor can easily provide an infinite number of speeds for the blower. In addition, the use of such a motor is desirable because it does .not require the frequentlubrication that electric motors require, it does not require the wiring and control equipment that electric motors require, and iti'snot as subject to attack by moisture, dirt and the like.

.In one form of the present invention a bypass is provided between the high pressure hydraulic line to the hydraulic motor and the low pressure hydraulic line from that motor; and .a valve is provided in that bypass. That valve can be closed to direct the entire output of the hydraulic pump to the inlet of the hydraulic motor and thereby drive that motor at top speed, it can be opened to bypass substantially all of the output of that pump and thereby let the hydraulic motor stop, or it can be moved to an infinite number of intermediate positions and thereby drive the hydraulic motor at a number of individually diiferent speeds. In that way, the valve in the bypass provides the required variation in the blower speed and thus in the volume of air passed over the condensing coil of the compression-expansion system.

C The valve in the bypass will preferably be made responsive to the pressure or temperature of the refrigerant in the high pressure side ofthe compression-expansion refrigeration system. Where that is; done, that valve can automatically respond to increases in that pressure or temperature to direct more of the output of the hydraulic pump to the hydraulic motor, thereby increasing the speed of that motor. Similarly, that valve can automatically respond to decreases in that pressure or temperature to divert more of the output of the hydraulic pump through the, bypass, thereby decreasing the speed of the hydraulic motor; This arrangement enables the blower'to speed up or slow down as'the pressureor temperature changesand thus enables the cooling apparatus to keep the pressureand temperature in the high side of the refrigeration system fairly constant. 7

The provision of the variable speed hydraulic motor as the source of power for the blower is important. In the first place, the bypassvalve will'usually be open at the beginning of a cycle of the compression-expansion refrigeration system and this -means that the source of power for the hydraulic pump has a very light starting load. It also means that the bypass valve will gradually close and start the blower smoothly and evenly. In the second place, the cooling apparatus will expend appreciable amounts of power only as long as the pressure or temperature of the refrigerant requires it, because the valve will be open and will, be bypassing the hydraulic fluid at all other times. In the third place the blower will operate at slow speeds and thus at low noise levels, when the ambientair is cool, as it can be .at night. This latter feature is particularly important in the field of residential air conditioning. In the fourth place, the blower may not have to operate at all, as when the weather turns cold.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

, In the drawing and accompanying description, two preferred embodiments of the present invention have been shown and described but it is to be understood that the "drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing, Fig. l is a schematic diagram of one form'of air cooling device that is made in accordance with the principles and teachings of the present invention, and v V 1 Fig. 2 is a schematicdiagram' of another form of air coolingdevice that is 'madein; accordance with the principles and teachings of thepresent'invention.

Referring to the drawing in detail, the numeral 10 de-' notes the compressor of a compression-expansion refrigeration system. That compressor is driven by an electric motor 12 to which it is connected by a belt or belts 14. Refrigerant passes from the high pressure outlet of the compressor 10 through a high pressure refrigerant line 16 to the inlet of a. condensing coil 18. The refrigerant then passes from the outlet of the condensing coil through a high pressure refrigerant .line .20 t0 the liquid receiver 22.. The liquid refrigerant will then pass from the receiver 22 through a high pressure refrigerant line 24 to an expansion valve 26, and will then enter the expansion coil 28. The refrigerant will expand in the coil 28; and low pressure refrigerant will pass through the low pressure refrigerant line 30 to the inlet of the compressor it The expansion valve 26 and the expansion coil 28 will be suitably located within a space to be cooled or refrigerated.

The numeral denotes an electric motor which drives a hydraulic pump 4-2. High pressure hydraulic fluid-passes from the pump 42 through a high pressure hydraulic line 44 to the inlet of hydraulic motor 46. That motor is mounted adjacent the condensing coil 18, and a blower 48 is mounted on the shaft of the motor 46. Low pressure hydraulic fluid will issue from the outlet of the motor 46, and itwill flow through alow pressure bydraulic line 50 and through an expansion tank 51 before it returns to. the inlet ofthe hydraulic pump 42. A

-T-junction 52 is provided in'the high pressure hydraulic line 44 and .a T-junction S4 is provided in the low pressurehydraulic. line 50. A bypass 56 extends between, and communicates with, the stems of the T-junctions 52 and 54; and a valve 58 is made a part' of that bypass.

In the particular modification shown, the valve 58 is normally open but can respond to increases in pressure to. close; and further, that valve can assume an infinite number of positions between open and closed positions.

A T-junction as is provided in the high pressure refrigerant line 16, and a small tube 62 extends between the T-junction 6t) and the valve 58. The tube 62 places the valve 58 in communication with the pressure of the refrigerant in the high pressure refrigerant line 16; and when that pressure rises to a predetermined value, the valve 58 will start to move toward closed position.

a In the operation of compression-expansion refrigeration systems shownin Fig. 1, the motors 12 and 40 will nor mally be at rest. When refrigeration effect is needed, the motors 12 and 40. will start, and the motor 12 will drive the compressor it}. Refrigerant will flow from the compressor to the condensing coil, and'will then flow through the receiver 22, the expansion valve 26, and the expansion coil 28 before it returns to the compressor 10. Initially, the condensing coil 18 will be cooler than the refrigerant, and hence that coil will absorb sufilcient heat from the refrigerant, to keep the pressure in the high pressure refrigerant line'16 below a predetermined level, as forv example, about one hundred and twenty five pounds per square .inch. However, as the compressor 10 continues to operate, the heat of the high pressure refrigerant quickly increases to the point where the heat-absorbing capacity of the metal in the condensing coil can not, by itself, hold the pressure of the refrigerant below one hundred and twenty five pounds per square inch. Thereupon; the refrigerant pressure at the'valve 58, which is also the pressure at the T-junction 6%), will start the valve 58 toward closing position.

Up to this moment, the motor 40 has not been doing .as the valve '58 starts to close, more and more of the hydraulic fluid from the output. of pump 42 will be directed to the hydraulic motor 46, and that motor will begin to rotate, The consequent rotation of the blower 48 will draw air through the condensing coil 18, and the cooling eflect of that air will enable that condensing coil to absorb additional heat from the high pressure refrigerant in that coil. If the amount of air being passed through the condensing coil 18 is not sufiicient to hold the pressure of the refrigerant close to one hundred and twenty five pounds per square inch, the pressure on the refrigerant will increase still further, thereby moving the valve 58 closer to closed position. This in turn will direct still more of the output of the hydraulic pump 42 to the motor 46, thereby increasing the speed of motor 46 and blower 48. In this way, the greater the need for cooling, as evidenced by increases in the pressure on the refrig-, erant in the high pressure refrigerant line 16, the faster the blower 48 will rotate and the more cooling eflect will be supplied. Very quickly, the speed of the blower 48 will increase to the point where the pressure of the refrigerant in the condensing coil, and thus in the high pressure sideof the compression-expansion refrigeration system, is held within the desired limits. The electric motor 40 will continue to run as long as the electric motor 12 operates, and the hydraulic motor 46 will hold the speed of the blower 48 at whatever value is needed to maintain the pressure in the high pressure side of the compression-expansion refrigeration system between the desired limits.

This equilibrium between the heat pumped into the refrigerant by the compressor and the heat removed from the refrigerant by the condensor and blower will be attained regardless of the temperature of the ambient air. Where the ambient air is hot, as it can be during the day the blower will rotate faster and will move more air per unit of time over the condensing coil. On the other hand, where the ambient air is cool, as it can be at night, the blower 48 will move less air per unit of time across the condensing coil. This means that the volume of air bears a relationship to the amount of heat that must be removed; and in this way the head pressure of the compressor can be kept within desirable limits.

, Referring to Fig. 2, the numeral 7 denotes an electric motor which operates a hydraulic pump 72. High pres sure hydraulic fluid issues from the outletof the pump 72 and enters the high pressure hydraulic line 74. That line conducts that hydraulic fluid to the inlet of a hydraulic motor 76. A blower 78 is mounted on the shaft of the motor 76, and that blower will rotate with that shaft. The low pressure hydraulic fluid which issues from the outlet of the motor 76 will be conducted by a low pressure hydraulic line 80 to an expansion tank 81 and thence to the inlet of the pump 72. T-junctions 83 are provided in high pressure hydraulic line 74 and low pressure bydraulic line 80, and those T-junctions are connected by a bypass 82. A valve 84 is provided as a part of that bypass. A thermally responsive bulb 86 is mounted adjacent the blower 78, and a tube 88 extends between the bulb 86 and the valve 84. In the particular modification shown, the valve 84 is normally open but can respond to increases in the temperature of the bulb 86 to close. Further, that valve is capable of assuming an infinite number of positions between open and closed positions.

The motor 70 will be suitably controlled by a switch, not shown; and one such switch could be the typical timer switch used for attic fans in residences. The motor 70 will usually be set to operate continuously for substantial periods of time, and when the temperature at the bulb 86. is below a predetermined level the valve 84 will be permitted to open. At such time, hydraulic fluid will pass from the outlet of the pump '72 to the bypass 82 and thence to the inlet of the pump 72 by means of the lower section of the low pressure hydraulic line 80. As long as the temperature at the bulb 86 is below the said predetermined level, the pump 72 will merely pump hydraulic fluid through the bypass. However, when the temperatrue at the bulb 86 rises above the said predetermined temperature, the thermal bulb will act through the tube 88 and the fluid therein to cause the valve 84 to start closing. As the valve 84 starts to close, some of the hydraulic fluid in the high pressure line 74 will be directed to the hydraulic motor 76, thereby causing that motor to start rotating. The blower 78 will rotate with the shaft of the motor 76, and that blower will move air that will have a cooling elfect on the ,bulb 86. If the cooling effect of that air is great enough, the temperature at the bulb will be caused to drop, the valve 84 will open, and the motor 76 will come to rest. If the cooling effect of that air is not great enough to cause the temperature of the bulb 86 to fall to the point where the valve 84 is permitted to open fully, that cooling elfec't can act to cool the bulb 86 and to cause a shifting of valve 84. In moving the air to cool the bulb 86, the blower 78 will cool the space from which it draws its air.

If the temperature of the air in that space were to rise, as it will do upon increases in the ambient temperatures outside that space, the temperature of the bulb 86 will increase and move the valve 84 closer to closed position. Such movement will increase the percent of hydraulic fluid directed to the hydraulic motor 76 and thereby cause it to rotate faster. This will cause an increase in the rate of rotation of the blower 78, and will increase the volume of air moved by that blower.

As the temperature of the ambient air falls, as it can during the night, the temperature of the bulb 86' will fall a corresponding amount. This will reduce the pressure on the valve 84 and will permit it to move toward open position. Such movement will enable more of the hydraulic fluid to pass through the bypass 82 and will reduce the amount of hydraulic fluid directed to the hydraulic motor 76. This will enable that motor to slow down and thereby enable the blower 78 to move less air per unit of time. That blower will still continue to move whatever air is necessary to maintain the bulb 86 at the desired temperature. However, it will not move any more air than necessary.

The hydraulic motors 46 and 76 will be practically noiseless in operation. Further, those motors will need little or no maintenance. Accordingly, the only noise that will be heard in the vicinity of the blowers 48 and 78 will be the noise which the air moved by those blowers will itself make. By proper dimensioning of the blowers 48 and 78, that noise can be held to a very low level.

Whereas the drawing and accompanying description have shown and described two preferred embodiments of the present invention, it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

1. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a hydraulic motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said hydraulic motor ,a hydraulic pump, a source of power for said hydraulic pump, a high pres-. sure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between and being in communication with both said high pressure hydraulic line and said low pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor, a pressure-responsive valve in said bypass, and a tube extending from said valve to a part of the high compression side of said compression-expansion system to place said valve in communication with the refrigerant pressure in said part of said system, said pressure-responsive valve being movable to open position to bypass the greatest part of the output of said hydraulic pump from said high pressure hydraulic line to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said blower and minimize cooling of said condensing coil and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said hydraulic motor and said blower at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed from said high pressure hydraulic line to said low pressure hydraulic line to thereby vary the speed of said hydraulic motor and of said blower, said valve being biased to open position but responding to increases in refrigerant pressure in said part of said compression-expansion system to move toward closed position, said valve and said hydraulic motor varying the speed of rotation of said blower to hold the refrigerant pressure in said part of said comprcssion-expansion system within predetermined limits.

2. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a hydraulic motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said hydraulic motor, a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between and being in communication with both said high pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor and said low pressure hydraulic line, a pressure-responsive valve in said bypass that is in communication with the refrigerant pressure in the high compression side of said compression-expansion system, said pressure-responsive valve being movable to bypass the greatest part of the output of said hydraulic pump to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said blower and minimize cooling of said condensing coil and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said hydraulic motor and said blower at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed to said low pressure hydraulic line to thereby vary the speed of said hydraulic motor and of said blower, said valve being biased to open position but responding to increases in refrigerant pressure to move toward closed position, said valve and said hydraulic motor varying the speed of rotation of said blower to hold the said refrigerant pressure within predetermined limits.

3. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a hydraulic motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said hydraulic motor, 'a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between and being in corn munication with both said high pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor and said low pressure hydraulic line, a valve in said bypass, said valve being movable to open position to bypass the greatest part of. the output of said hydraulic pump from said high pressure hydraulic line to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said blower and minimize cooling of said condensing coil and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said hydraulic motor and said blower at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed from said high pressure hydraulic line to said low pressure hydraulic line to thereby vary the speed of said hydraulic motor and of said blower, said valve and said hydraulic motor coacting to vary the speed of rotation of said blower and hold the refrigerant pressure in the high compression side of said compression-expansion system within predetermined limits.

4. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a hydraulic motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said hydraulic motor, a hydraulic pump, a source of power for said hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between and being in communication with both said high pressure hydraulic line and said low pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor, and a condition-responsive valve in said bypass, said valve being movable to open position to by pass the greatest part of the output of said hydraulic pump from said high pressure hydraulic line to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said blower and minimize cooling of said condensing coil and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said hydraulic motor and said blower at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed from said high pressure hydraulic line to said low pressure hydraulic line and to thereby vary the speed of said hydraulic motor and of said blower, said valve responding to predetermined conditions to cause said hydraulic motor to vary the speed of rotation of said blower and thereby adjust the cooling effect on the refrigerant in said expansion coil.

5. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a hydraulic motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said hydraulic motor, a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass between and being in communication with both said high pressure hydraulic line and said low pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor, and a valve in said bypass to regulate the bypassing of hydraulic fluid from said high pressure hydraulic line to said low pressure hydraulic line to vary the speed of said motor and of said blower and thereby vary the cooling of said expansion coil, said valve being adapted to provide a plurality of individually different speeds for said motor and said blower.

6. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said motor, and a pressure-responsive control that varies the speed of said motor and therefore of said blower, said control being in communication with the refrigerant pressure in a high pressure part of said compression-expansion system and responding to increases in said refrigerant pressure to increase the speed of said motor and of said blower and responding to decreases in said refrigerant pressure to decrease the speed of said motor and of said blower, whereby said control varies the speed of said motor and of said blower and thereby holds said refrigerant pressure within predetermined limits, said control being adapted to provide a plurality of individually different speeds for said motor and said blower.

7. In a compression-expansion cooling system that includes a compressor, a condensing coil and an expansion coil, the improvement which comprises a rotating device that drives said compressor, a hydraulic motor adjacent said condensing coil, a blower mounted on and rotatable with the shaft of said motor, a hydraulic pump connected to said motor to drive same, and a pressure-responsive hydraulic bypass that varies the percentages of the output of said hydraulic pump that are directed to said hydraulic motor and that are bypassed to said hydraulic pump and that thereby varies the speed of said motor and therefore of said blower, said bypass being responsive to the refrigerant pressure in a high pressure part of said compression-expansion system and responding to increases in said refrigerant pressure to increase the speed of said motor and of said blower and responding to decreases in said refrigerant pressure to decrease the speed of said motor a and of said blower, said bypass being adapted to provide a plurality of individually dilferent speeds for said motor and said blower.

8. An air-cooled condensing coil for a compressionexpansion cooling system which comprises a compressor, a finned coil, a rotating device that drives said compressor, a hydraulic motor mounted adjacent said coil, a blower that is mounted on and rotatable with the shaft of said motor, a hydraulic pump, a source of power for said hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between both said high pressure hydraulic line and said low pressure bydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor, and a valve in said bypass, said valve being adjustable to bypass from said high pressure hydraulic line to said low pressure hydraulic line substantially 'all or none of the hydraulic fluid pumped by said hydraulic pump whereby said hydraulic pump can operate without rotation of said shaft of said hydraulic motor or can drive said shaft at top speed, said valve being adapted to provide a plurality of individually different speeds for said motor and said blower.

9. An aircooled condensing coil for a compressionexpansion cooling system that comprises a compressor, a finned coil, a rotating device that drives said compressor, a hydraulic motor mounted adjacent said coil, a blower mounted on and rotatable with the shaft of said hydraulic motor, a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between both said high pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor and said low pressure hydraulic line, and a pressure-responsive valve in said bypass that is responsive to refrigerant pressure in the high side of said compression-expansion system, said valve opening as the refrigerant pressure in the said high side of said compression-expansion system decreases and closing as the refrigerant pressure in the said high side of said compression-expansion system increases, whereby a substantially constant refrigerant pressure is maintained in said high side ofsaid compression-expansion system when the compressor thereof is operating, said valve being adapted to provide a plurality of individually different speeds for said motor and said blower.

10. A temperature-regulating, variable speed cooling device that comprises a hydraulic motor, an air-moving device mounted on and rotatable with the shaft of said motor, said air-moving device moving air through a space, a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between and being in communication with both said high pressure hydraulic line and said low pressure hydraulic line and being adapted to conduct some of the output of said hy-, draulic pump to said low pressure line while the rest of said output flows to said hydraulic motor, a temperatureresponsive valve in said bypass, and a temperature-sensing element that is in said space and that is connected to and controls said valve in said bypass, said valve being movable to open position to bypass the greatest part of the output of said hydraulic pump from said high pressure hydraulic line to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said air-moving device and minimize cooling of said space and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said bydraulic motor and said air-moving device at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed from said high pressure hydraulic line to said low pressure hydraulic line and to thereby vary the speed of said hydraulic motor and of said air-moving device and to thereby vary the cooling of said space, said valve being biased to open position but responding to increases in temperature to move toward closed position, said valve and said hydraulic motor varying the speed of rotation of said air-moving device to hold the temperature of said space within predetermined limits.

11. A temperatureregulating, variable speed cooling device that comprises a hydraulic motor, an air-moving device mounted on and rotatable with the shaft of said motor, said air-moving device moving air through a space, a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending between and being in communication with both said high pressure hydraulic line and said low pressure hydraulic line and being adapted to conduct some of the output of said hydraulic pump to said low pressure line while the rest of said output flows to said hydraulic motor, a variable valve in said bypass, and a temperature-sensing element that is in said space and that is connected to and controls said valve in said bypass, said valve being movable to open position to bypass the greatest part of the output of said hydraulic pump from said high pressure hydraulic line to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said air-moving device and minimize cooling of said space and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said hydraulic motor and said air-moving device at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed from said high pressure hydraulic line to said low pressure hydraulic line and to thereby vary the speed of said hydraulic motor and of said air-moving device and to thereby vary the cooling of said space, said valve being biased to open position but responding to a change in 1 1 conditions to move toward closed position, said valve and said hydraulic motor varying the speed of rotation of said air-moving device to maintain said condition within predetermined limits. 1

12. A temperature-regulating, variable speed cooling device that oomprises a hydraulic motor, an air-moving device mounted on and rotatable with the shaft of said motor, said air-moving device moving air through a space, a hydraulic pump, a high pressure hydraulic line extending from the outlet of said hydraulic pump to the inlet of said hydraulic motor, a low pressure hydraulic line extending from the outlet of said hydraulic motor to the inlet of said hydraulic pump, a bypass extending to said low pressure hydraulic line to conduct some of the output of said hydraulic pump to said low pressure hydraulic line while the rest of said output flows to the inlet of said hydraulic motor, a variable valve insaid bypass, and a temperature-sensing element that is in said space and that is connected to and controls said valve in said bypass, said valve being movable to open position to bypass the greatest part of the output of said hydraulic pump from said high pressure hydraulic line to said low pressure hydraulic line to thereby deenergize said hydraulic motor and said air-moving device and minimize cooling of said space and being movable to closed position to direct the output of said hydraulic pump to said hydraulic motor to drive said hydraulic motor and said air-moving device at top speed and being movable to a number of intermediate positions to regulate the percentage of the output of said hydraulic pump that is bypassed from said high pressure hydraulic line to said low pressure hydraulic line and to thereby vary the speed of said hydraulic motor and of said air-moving device and to thereby vary the cooling of said space, said valve and said hydraulic motor varying the speed of rotation of said air-moving device to regulate the cooling effect provided by said air-moving device.

References Cited in the file of this patent UNITED STATES PATENTS 1,256,709 Ludeman Feb. 19, 1918 2,104,696 Hanson Jan. 4, 1938 2,210,325 Newton Aug. 6, 1940 2,212,503 Nickell Aug. 27, 1940 2,406,486 Bonham Aug. 27, 1946 2,594,460 Lauck Apr. 29, 1952 2,705,404 Malutich Apr. 5, 1955 

